As semiconductor devices, such as processors and processing elements, operate at continually higher data rates and higher frequencies, greater current is consumed and more heat is produced. Due to size and location restrictions, as well as thermal limitations, conventional heat transfer mechanisms for packaged devices (i.e., dies) have a limited heat transfer capability restricting the operation of such devices to lower power levels, lower data rates and/or lower operating frequencies. As the performance of dies increases, materials with lower dielectric constants may be integrated into the die surface. These lower dielectric materials tend to be either more brittle or less stiff than those used previously, and may break more easily or deform by large amounts as a result of thermal expansion mismatches between the various materials in the package.
One problem with conventional packages is the heat dissipation path itself. Some conventional packaging techniques dissipate heat generated within a die using an integrated heat spreader which may be thermally bonded to the side of the die opposite the substrate. In many cases, however, most of the heat generated within the die is generated on the substrate side of the die, rather than the heat spreader side of the die. This increased heat dissipation path reduces the heat dissipation ability of the package. It may also increase the operating temperature of the die, and may restrict the operation of the die to lower power levels, lower data rates and/or lower operating frequencies.
Another problem with conventional organic-based packages is the thermal expansion mismatch between the die and the substrate. This is especially a problem for die coated with lower dielectric constant materials. Conventional packaging techniques have used a ceramic, rather than organic, substrate to reduce the thermal expansion mismatch. More recently, interconnects have been introduced between the substrate and die that reduce the thermal stresses on the die and the dielectric layer. These interconnects are sometimes referred to as “compliant” interconnects because they may comply with their surroundings. Although these interconnects may reduce the thermal stresses on the die, they have poor heat dissipation abilities making it difficult to remove heat from the substrate side of the die where most heat may be generated.
Thus, there are general needs for improved packages and methods for dissipating heat within a package. There is also a need for a package and method that helps reduce the temperature of a die. There is also a need for a package and method that removes heat from the substrate side of a die. There is also a need for a package and method that helps reduce stress on a die caused by thermal mismatches. There is also a need for a package and method that increases the reliability of a die. There is also a need for a package and method that allows a die to operate at higher data rates. There is also a need for a package and method suitable for die incorporating lower dielectric constant materials.